Adam Van Ymeren
7a04f298d2
- update to latest telegram layer - remove some references to fields in tg.Entities that don't exist in the schema - originally added here: https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e - referenced here - https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3 - https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e
63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
package crypto
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import (
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"bytes"
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"crypto/rsa"
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"crypto/sha1" // #nosec G505
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"io"
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"github.com/go-faster/errors"
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)
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// RSAEncryptHashed encrypts given data with RSA, prefixing with a hash.
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func RSAEncryptHashed(data []byte, key *rsa.PublicKey, randomSource io.Reader) ([]byte, error) {
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// Preparing `data_with_hash`.
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// data_with_hash := SHA1(data) + data + (any random bytes);
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// such that the length equals 255 bytes;
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var dataWithHash [rsaWithHashLen]byte
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if len(data) > rsaDataLen {
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return nil, errors.Errorf("data length %d is too big", len(data))
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}
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// Filling data_with_hash with random bytes.
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if _, err := io.ReadFull(randomSource, dataWithHash[:]); err != nil {
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return nil, err
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}
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h := sha1.Sum(data) // #nosec
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// Replacing first 20 bytes with sha1(data).
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copy(dataWithHash[:sha1.Size], h[:])
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// Replacing other bytes with data itself.
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copy(dataWithHash[sha1.Size:], data)
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// Encrypting "dataWithHash" with RSA.
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res := rsaEncrypt(dataWithHash[:], key)
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return res, nil
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}
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// RSADecryptHashed decrypts given data with RSA.
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func RSADecryptHashed(data []byte, key *rsa.PrivateKey) ([]byte, error) {
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var dataWithHash [rsaWithHashLen]byte
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if !rsaDecrypt(data, key, dataWithHash[:]) {
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return nil, errors.New("invalid data_with_hash")
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}
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hash := dataWithHash[:sha1.Size]
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paddedData := dataWithHash[sha1.Size:]
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// Guessing such data that sha1(data) == hash.
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for i := 0; i <= len(paddedData); i++ {
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data := paddedData[:len(paddedData)-i]
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h := sha1.Sum(data) // #nosec
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if bytes.Equal(h[:], hash) {
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// Found.
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return data, nil
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}
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}
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// This can be caused by invalid keys or implementation bug.
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return nil, errors.New("hash mismatch")
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}
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